Nonwoven Abrasive Articles and Methods of Making the Same

ABSTRACT

Nonwoven abrasive articles comprise a nonwoven abrasive member having an overlayer composition comprising a fatty acid metal salt disposed thereon adjacent to a working surface. The nonwoven abrasive member comprises abrasive particles adhered to a fiber web by a binder. The abrasive particles may be exposed and/or the nonwoven abrasive member may have suitable frictional properties. Methods of making the same are also disclosed.

TECHNICAL FIELD

The present disclosure relates broadly to nonwoven abrasive articles andmethods of making them.

BACKGROUND

Nonwoven abrasive articles comprising a three-dimensional fiber webbonded at contact points between adjacent fibers are used extensively inthe manufacture of abrasive articles for cleaning, abrading, finishingand polishing applications on any of a variety of surfaces. In additionto the nonwoven web, the nonwoven abrasive articles generally includeabrasive particles and a binder material (commonly termed a “binder”)that bonds the fibers within the nonwoven web to each other and securesthe abrasive particles to the nonwoven web.

One common type of nonwoven abrasive includes a lofty open fiber web.Exemplary of such nonwoven abrasive articles are those described in U.S.Pat. No. 2,958,593 (Hoover et al.). Exemplary commercial nonwovenabrasive articles include nonwoven abrasive hand pads such as thosemarketed by 3M Company of Saint Paul, Minn. under the trade designationSCOTCH-BRITE.

Other examples of nonwoven abrasive articles include convolute abrasivewheels and unitized abrasive wheels. Nonwoven abrasive wheels typicallyhave abrasive particles distributed through the layers of nonwoven webbonded together with a binder that bonds layers of nonwoven webstogether, and likewise bonds the abrasive particles to the nonwoven web.Unitized abrasive wheels have individual discs of nonwoven web arrangedin a parallel fashion to form a cylinder having a hollow axial core.Alternatively, convolute abrasive wheels have a nonwoven web that isspirally wound about and affixed to a core member.

Regardless of the construction of the nonwoven abrasive articles, theirabrading performance generally decreases over time with use. Acontinuing need exists for ways to extend the useful abrading life ofnonwoven abrasive articles.

SUMMARY

The present inventors have discovered that application of an overlayercomposition comprising a metal stearate to nonwoven abrasive articleshaving abrasive particles that are not deeply submerged within thebinder material improves abrading performance, while in cases where theabrasive particles that are deeply submerged, addition of the sameoverlayer composition results in degraded abrading performance.

In one aspect, the present disclosure provides a nonwoven abrasivearticle comprising:

a) a nonwoven abrasive member having a working surface, wherein thenonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;    -   abrasive particles adhered to at least a portion of the fibers        by a binder material, wherein at least a portion of the abrasive        particles form a visible outer layer of the abrasive particles        along the fibers adjacent to the working surface of the nonwoven        abrasive member, wherein the abrasive particles in the visible        outer layer are closely packed, and wherein on a numerical basis        at least 80 percent of the abrasive particles in the visible        outer layer have recognizable outlines; and

b) an overlayer composition disposed on at least a portion of thevisible outer layer of the abrasive particles thereby forming thenonwoven abrasive article, wherein the overlayer composition comprises afatty acid metal salt.

In another aspect, the present disclosure provides a method of making anabrasive article, the method comprising sequentially:

a) providing a nonwoven abrasive member having a working surface,wherein the nonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;    -   abrasive particles adhered to at least a portion of the fibers        by a binder material, wherein at least a portion of the abrasive        particles form a visible outer layer of the abrasive particles        along the fibers adjacent to the working surface of the nonwoven        abrasive member, wherein the abrasive particles in the visible        outer layer are closely packed, and wherein on a numerical basis        at least 80 percent of the abrasive particles in the visible        outer layer have recognizable outlines; and    -   b) disposing an overlayer composition on at least a portion of        the visible outer layer of the abrasive particles thereby        forming the nonwoven abrasive article, wherein the overlayer        composition comprises a fatty acid metal salt.

The present inventors have further developed a convenient test that canpredict which nonwoven abrasive articles will benefit from applicationof a metal-stearate containing overlayer composition.

Accordingly, in yet another aspect, the present disclosure provides anonwoven abrasive article comprising:

a nonwoven abrasive member having a working surface, wherein thenonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;        and    -   abrasive particles adhered to the fibers by a binder material,        wherein the working surface of the nonwoven abrasive member has        a kinetic coefficient of friction of at least 0.54 according to        the FRICTION TEST described herein; and

an overlayer composition disposed on at least a portion of the bindermaterial and abrasive particles adjacent to the working surface therebyforming the nonwoven abrasive article, wherein the overlayer compositioncomprises a fatty acid metal salt.

Likewise, in yet another aspect, the present disclosure provides amethod of making an abrasive article, the method comprisingsequentially:

providing a nonwoven abrasive member having a working surface, whereinthe nonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;    -   abrasive particles adhered to the fibers by a binder material,        wherein the working surface of the nonwoven abrasive member has        a kinetic coefficient of friction of at least 0.54 according to        the FRICTION TEST described herein; and

disposing an overlayer composition on at least a portion of the bindermaterial and the abrasive particles adjacent to the working surfacethereby forming the nonwoven abrasive article, wherein the overlayercomposition comprises a fatty acid metal salt.

In view of the above, the present disclosure also provides a method ofmaking an abrasive article, the method comprising:

a) providing a nonwoven abrasive member having a working surface,wherein the nonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;        and    -   abrasive particles adhered to at least a portion of the fibers        by a binder material, wherein at least a portion of the abrasive        particles are at least partially embedded in the binder        material; and

b) plasma-etching a portion of the binder material adjacent to theworking surface to expose portions of the abrasive particles previouslyembedded in the binder material to provide a plasma-etched nonwovenabrasive member; and

c) disposing an overlayer composition on at least a portion of theworking surface of the plasma-etched nonwoven abrasive member, whereinthe overlayer composition comprises a fatty acid metal salt.

As used herein, the term “closely packed” in reference to abrasiveparticles means that substantially all of the abrasive particles arewithin a distance (between outer surfaces) of one average particlediameter to the nearest abrasive particle, but does not necessarily meanthat the abrasive particles are in the closest theoretically possiblepacking arrangement.

As used herein, the term “recognizable outline” in reference to anabrasive particle means that the peripheral outline of the abrasiveparticle as viewed from at least one direction is discernible at amagnification of 150 times (i.e., 150×) by a human eye having 20/20vision.

For example, the abrasive particles are not substantially submerged in amass of binder material, although they may have a thin (e.g.,substantially uniform) coating of binder covering them if it conforms tothe shapes of the abrasive particles.

As used herein, the FRICTION TEST is as follows:

Test specimens of nonwoven abrasive members and polymethyl methacrylatediscs to be used in this test procedure are equilibrated for at least 24hours at 17 percent relative humidity and 25° C. prior to use. Astandard testing surface is prepared by attaching a 4-inch (10.2 cm)diameter by ⅛-inch (3.2-mm) thick polymethyl methacrylate (PMMA) disc, MBall hardness 90-105 onto a horizontal test stage such that it cannotmove relative to the stage during the test. The surface roughness of thePMMA surface is: R_(a)=0.384+/−0.08 microinch (0.0098+/−0.002 micron),R_(z)=3.95+/−0.32 microinches (0.100+/−0.008 micron),R_(max)=6.09+/−0.67 microinches (0.155+/−0.017 micron). Next, a 2inches×2 inches (5 cm×5 cm) area test specimen is cut from a nonwovenabrasive member to be tested and affixed to a 2 inches×2 inches (5 cm×5cm) 500-gram metal weight using double-sided pressure-sensitive adhesivetape, assuring that the 2 inches×2 inches area of the test specimen isadjacent to the metal weight.

The weighted test specimen is placed, with a working surface (i.e., asurface of the nonwoven abrasive member intended to abrade a workpiece)in contact with the PMMA disc, on the test surface and attached to theload cell of a friction testing machine (e.g., a Thwing-AlbertFriction/Peel Tester Model 225-100 from Thwing-Albert InstrumentCompany, West Berlin, N.J. or a functional equivalent) at 17 percentrelative humidity and 25° C. Horizontal force is applied by the frictiontesting machine at a horizontal stage translational speed of 31cm/minute and the kinetic coefficient of friction is determined as theaverage kinetic coefficient of friction over a 5-second intervals.Nonwoven abrasive members typically have one working surface (e.g.,belts) or two working surfaces (e.g., hand pads). In the case that thenonwoven abrasive member has multiple working surfaces, any workingsurface may be used.

FIG. 24 shows an exemplary configuration for carrying out the FRICTIONTEST described above. Referring now to FIG. 24, PMMA disc 2420 isattached to horizontal test stage 2450. The nonwoven abrasive membertest specimen 2410 is placed upon PMMA disc 2420 and metal weight 2400is secured with double-sided tape 2415 to test specimen 2410. Horizontalrod 2430 is attached to the friction testing device load cell 2460 andmetal weight 2400. Force is applied along direction 2470 by the frictiontesting machine during the test.

Features and advantages of the present disclosure will be furtherunderstood upon consideration of the detailed description as well as theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of an exemplary nonwoven abrasive article100 according to the present disclosure;

FIG. 1B is an enlarged view of region 1B of nonwoven abrasive article100 shown in FIG. 1A;

FIG. 1C is a cross-sectional view of bonded fibers shown in FIG. 1Btaken along line 1C-1C.

FIGS. 2 and 3 are Scanning Electron Microscope (SEM) micrographs of thenonwoven abrasive members used in Examples 1 and 2, respectively.

FIGS. 4 and 5 are SEM micrographs of the respective nonwoven abrasivemembers used in Comparative Examples A and B.

FIGS. 6-7 are SEM micrographs of the respective nonwoven abrasivemembers used in Examples 3 and 4.

FIG. 8 is an SEM micrograph of the nonwoven abrasive member used inExample 5.

FIGS. 9-11 are SEM micrographs of the respective nonwoven abrasivemembers used in Examples 6-8.

FIG. 12 is a SEM micrograph of the nonwoven abrasive member used inComparative Example C.

FIGS. 13-23 are SEM micrographs of the respective nonwoven abrasivemembers used in Examples 9-23.

FIG. 24 is a schematic view of a configuration for carrying out theFRICTION TEST.

Repeated use of reference characters in the specification and drawingsis intended to represent the same or analogous features or elements ofthe disclosure. It should be understood that numerous othermodifications and embodiments can be devised by those skilled in theart, which fall within the scope and spirit of the principles of thedisclosure. The figures may not be drawn to scale.

DETAILED DESCRIPTION

Referring now to FIGS. 1A-1C, exemplary nonwoven abrasive article 100comprises nonwoven abrasive member 110. The nonwoven abrasive member 110comprises lofty open fiber web 120 comprising fibers 130 bonded to oneanother. Nonwoven abrasive member 110 has first and second opposedworking surfaces 142, 144. Abrasive particles 150 are adhered to fibers130 by binder material 155.

In some embodiments, shown in FIGS. 1A-1C, abrasive particles 150adjacent to working surfaces 142, 144 form a visible outer layer 165 ofabrasive particles 150 along fibers 130. Abrasive particles 150 invisible outer layer 165 are closely packed and have recognizableoutlines 170 (see also FIG. 10). Overlayer composition 160 comprises afatty acid metal salt, and is disposed on at least a portion of bindermaterial 155 and abrasive particles 150 adjacent to working surfaces 142and 144 of nonwoven abrasive member 110.

In some embodiments, on a numerical basis the percentage of abrasiveparticles in the visible outer layer may be at least 80 percent, atleast 85 percent, at least 90 percent, at least 95 percent, at least 97percent, or 99 percent, or even 100 percent.

In some embodiments, crevices are disposed between adjacent abrasiveparticles in the visible outer layer. For example, referring to FIG. 10,crevices 180 are disposed between adjacent abrasive particles 150.

In some embodiments, at least a portion of the abrasive particles in thevisible outer layer of the abrasive particles overlap one another, forexample, as shown in FIG. 15, wherein abrasive particles 150 overlapadjacent abrasive particles.

In some embodiments, at least one of working surfaces 142, 144 has akinetic coefficient of friction which may be at least 0.54 according tothe FRICTION TEST described herein.

The lofty open fiber web is a lofty nonwoven fibrous material having asubstantially continuous network of voids extending therethrough. By useof the term “lofty open fiber web”, what is intended is a layer ofnonwoven web material composed of a plurality of randomly orientedfibers, typically entangled, having a substantially continuous networkof interconnecting voids extending therethrough.

Nonwoven fiber webs are typically selected to be suitably compatiblewith adhering binders and abrasive particles while also beingprocessable in combination with other components of the article, andtypically can withstand processing conditions (e.g., temperatures) suchas those employed during application and curing of the curablecomposition. The fibers may be chosen to affect properties of theabrasive article such as, for example, flexibility, elasticity,durability or longevity, abrasiveness, and finishing properties.Examples of fibers that may be suitable include natural fibers,synthetic fibers, and mixtures of natural and/or synthetic fibers.Examples of synthetic fibers include those made from polyester (e.g.,polyethylene terephthalate), polyamides (e.g., nylon 6, nylon 6/6, andnylon 10), polyolefins (e.g., polyethylene, polypropylene, andpolybutylene), acrylic polymers (e.g., polyacrylonitrile and copolymerscontaining acrylic monomers), rayon, cellulose acetate, polyvinylidenechloride-vinyl chloride copolymers, and vinyl chloride-acrylonitrilecopolymers. Examples of suitable natural fibers include cotton, wool,jute, and hemp. The fibers may be of virgin material or of recycled orwaste material, for example, reclaimed from garment cuttings, carpetmanufacturing, fiber manufacturing, or textile processing. The fibersmay be homogenous or a composite such as a bicomponent fiber (e.g., aco-spun sheath-core fiber). The fibers may be tensilized and crimped.They may be chopped fibers (i.e., staple fibers) or continuous filamentssuch as those formed by an extrusion process. Combinations of fibers mayalso be used.

The fibers may comprise continuous fiber, staple fiber, or a combinationthereof. For example, the fiber web may comprise staple fibers having alength of at least about 20 millimeters (mm), at least about 30 mm, orat least about 40 mm, and less than about 110 mm, less than about 85 mm,or less than about 65 mm, although shorter and longer fibers (e.g.,continuous filaments) may also be useful. The fibers may have a finenessor linear density of at least about 1.7 decitex (dtex, i.e., grams/10000meters), at least about 6 dtex, or at least about 17 dtex, and less thanabout 560 dtex, less than about 280 dtex, or less than about 120 dtex,although fibers having lesser and/or greater linear densities may alsobe useful. Mixtures of fibers with differing linear densities may beuseful, for example, to provide a nonwoven abrasive article that uponuse will result in a specifically preferred surface finish.

Nonwoven fiber webs may be made, for example, by conventional air laid,carded, stitch bonded, spun bonded, wet laid, and/or melt blownprocedures. Air laid fiber webs may be prepared using equipment such as,for example, that available as a RANDO WEBBER from Rando Machine Companyof Macedon, N.Y.

Frequently, as known in the abrasive art, it is useful to apply apre-bond resin to the nonwoven fiber web prior to coating with thecurable composition. The pre-bond resin serves, for example, to helpmaintain the nonwoven fiber web integrity during handling, and may alsofacilitate bonding of the urethane binder to the nonwoven fiber web.Examples of pre-bond resins include phenolic resins, urethane resins,hide glue, acrylic resins, urea-formaldehyde resins,melamine-formaldehyde resins, epoxy resins, and combinations thereof.The amount of pre-bond resin used in this manner is typically adjustedto bond the fibers together at their points of crossing contact. Inthose cases, wherein the nonwoven fiber web includes thermally bondablefibers, thermal bonding of the nonwoven fiber web may also be helpful tomaintain web integrity during processing.

The lofty open fiber web typically has a thickness of at least 3 mm,more typically at least 6 millimeters, and more typically at least 10millimeters, although other thicknesses may also be used. Commonthicknesses for the lofty open fiber web are, for example, 6.35 mm (¼inch) and 12.7 mm (½ inch). Addition of a pre-bond binder onto thefibrous mat does not significantly alter the thickness of the lofty openfiber web.

The basis weight of the lofty open fiber web (fibers only, with nopre-bond binder layer) is typically from about 50 grams per square meterto about 1 kilogram per square meter, and more typically from about 70to about 600 grams per square meter, although other basis weights mayalso be used. Typically, a pre-bond binder is applied to the lofty openfiber web to lock the fibers. The basis weight of the lofty open fiberweb, with pre-bond binder, is typically from about 60 grams per squaremeter to about 2 kilogram per square meter, and more typically fromabout 80 grams to about 1.5 kilogram per square meter, although this isnot a requirement.

The lofty open fiber web can be prepared by any suitable web formingoperation. For example the lofty open fiber web may be carded,spunbonded, spunlaced, melt blown, air laid, or made by other processesas are known in the art. For example, the lofty open fiber web may becross-lapped, stitchbonded, and/or needletacked.

Useful abrasive particles may be organic or inorganic particles.Examples of suitable inorganic abrasive particles include alumina oraluminum oxide, (such as fused aluminum oxide, heat treated fusedaluminum oxide, ceramic aluminum oxide, heat treated aluminum oxide),silicon carbide, titanium diboride, alumina zirconia, diamond, boroncarbide, ceria, aluminum silicates, cubic boron nitride, garnet, silica,and combinations thereof. The abrasive particles may be in the form of,for example, individual particles, agglomerates, composite particles,and mixtures thereof. Preferred fused aluminum oxides include thoseavailable commercially pretreated by Exolon ESK Company, Tonawanda,N.Y., or Washington Mills Electro Minerals Corp., Niagara Falls, N.Y.Preferred ceramic aluminum oxide abrasive particles include thosedescribed in U.S. Pat. No. 4,314,827 (Leitheiser); U.S. Pat. No.4,623,364 (Cottringer et al.); U.S. Pat. No. 4,744,802 (Schwabel etal.); U.S. Pat. No. 4,770,671 (Monroe et al.); U.S. Pat. No. 4,881,951(Monroe et al.); U.S. Pat. No. 4,964,883 (Morris et al.); U.S. Pat. No.5,011,508 (Wald et al.); and U.S. Pat. No. 5,164,348 (Wood).

Organic abrasive particles suitable for use in abrasive article arepreferably formed from a thermoplastic polymer and/or a thermosettingpolymer. Organic abrasive particles can be formed from a thermoplasticmaterial such as polycarbonate, polyetherimide, polyester, polyvinylchloride (PVC), polymethyl methacrylate, polyethylene, polysulfone,polystyrene, acrylonitrile-butadiene-styrene block copolymer,polypropylene, acetal polymers, polyurethanes, polyamide, andcombinations thereof. The organic abrasive particle may be a mixture ofa thermoplastic polymer and a thermosetting polymer.

The abrasive particles, either inorganic or organic, can have anyprecise shape or can be irregularly or randomly shaped. Examples of suchthree-dimensional shapes include: pyramids, cylinders, cones, spheres,blocks, cubes, polygons, and the like. Alternatively, the organicabrasive particles can be relatively flat and have a cross sectionalshape such as a diamond, cross, circle, triangle, rectangle, square,oval, octagon, pentagon, hexagon, polygon and the like. Shaped abrasiveparticles, and methods of making them, are taught in U.S. Pat. No.5,009,676 (Rue et al.); U.S. Pat. No. 5,185,012 (Kelly); U.S. Pat. No.5,244,477 (Rue et al.); U.S. Pat. No. 5,372,620 (Culler et al.); U.S.Pat. No. 8,142,531 B2 (Adefris et al.); U.S. Pat. No. 8,142,532 B2(Boden et al.); U.S. Pat. No. 8,123,828 B2 (Culler et al.); and U.S.Pat. No. 8,034,137 B2 (Erickson et al.); and in U.S. Patent Appin. Publ.Nos. 2010/0146867 A1 (Boden et al.) and 2010/0151195 A1 (Culler et al.).Shaped thermosetting organic abrasive particles can be made inaccordance with U.S. Pat. No. 5,500,273 (Holmes et al.).

The surface of the abrasive particles (a portion of their surface, orthe entire surface) may be treated with coupling agents to enhanceadhesion to and/or dispersibility in the binder material.

The abrasive particles may be of any size. They may comprise a mixtureof chemically-different particles. For a given composition, the abrasiveparticle size distribution may be monomodal or polymodal (e.g.,bimodal). The abrasive particles may, for example, have an averagediameter of at least about 0.1 micron, at least about 1 micron, at leastabout 5 microns, or at least about 10 microns, and/or less than about2000, less than about 1300 microns, or less than about 1000 microns,although larger and smaller abrasive particles may also be used. Forexample, the abrasive particles may have an abrasives industry specifiednominal grade. Such abrasives industry accepted grading standardsinclude those known as the American National Standards Institute, Inc.(ANSI) standards, Federation of European Producers of Abrasive Products(FEPA) standards, and Japanese Industrial Standard (JIS) standards.Exemplary ANSI grade designations (i.e., specified nominal grades)include: ANSI 4, ANSI 6, ANSI 8, ANSI 16, ANSI 24, ANSI 36, ANSI 40,ANSI 50, ANSI 60, ANSI 80, ANSI 100, ANSI 120, ANSI 150, ANSI 180, ANSI220, ANSI 240, ANSI 280, ANSI 320, ANSI 360, ANSI 400, and ANSI 600.Exemplary FEPA grade designations include P8, P12, P16, P24, P36, P40,P50, P60, P80, P100, P120, P150, P180, P220, P320, P400, P500, 600,P800, P1000, and P1200. Exemplary JIS grade designations include JIS8,JIS12, JIS16, JIS24, JIS36, JIS46, JIS54, JIS60, JIS80, JIS100, JIS150,JIS180, JIS220, JIS240, JIS280, JIS320, JIS360, JIS400, JIS400, JIS600,JIS800, JIS1000, JIS1500, JIS2500, JIS4000, JIS6000, JIS8000, and JIS10000.

Typically, the coating weight for the abrasive particles (independent ofother ingredients in the curable composition) may depend, for example,on the particular binder precursor used, the process for applying theabrasive particles, and the size of the abrasive particles. For example,the coating weight of the abrasive particles on the nonwoven fiber web(before any compression) may be at least 50 grams per square meter(gsm), at least 200 gsm, or at least 400 gsm; and/or less than 2000 gsm,less than about 1600 gsm, or less than about 1200 gsm, although othercoating weights may be also be used.

The abrasive particles are adhered to the fiber web by the bindermaterial that is typically derived from a thermosetting (e.g.,polymerizable and/or cross-linkable) organic binder precursor, which ishardened or cured to form the binder material. During the manufacture ofabrasive articles, the binder precursor is exposed to an energy sourcewhich aids in the initiation of the polymerization or curing process.Examples of energy sources include thermal energy and radiation energy.During this polymerization process, the binder precursor is polymerizedand converted into a solidified binder. Once cured, the resultant binderis generally non-tacky.

Examples of binder precursors that may be at least partially cured toform the binder material include condensation curable materials and/oraddition polymerizable materials. Such binder precursors may besolvent-based, water-based, or 100 percent solids. Examples of organicresins suitable for use in the binder precursor/binder include phenolicresins (both resoles and novolacs), urea-formaldehyde resins,melamine-formaldehyde resins, urethanes, acrylated urethanes, acrylatedepoxies, ethylenically-unsaturated compounds (acrylic and methacrylicmonomers, aminoplast derivatives having pendant unsaturated carbonylgroups, isocyanurate derivatives having at least one pendant acrylategroup, isocyanate derivatives having at least one pendant acrylategroup, vinyl ethers, epoxy resins, mixtures and combinations thereof.Other materials not within these groups may also be suitable in thebinder.

Exemplary phenolic resins suitable for use in binder precursors includeresole phenolic resins and novolac phenolic resins. Exemplarycommercially available phenolic materials include those having the tradedesignations DUREZ or VARCUM (available from Occidental ChemicalCorporation, Dallas, Tex.); RESINOX (available from Monsanto Company,St. Louis, Mo.); AROFENE or AROTAP (available from Ashland ChemicalCompany, Columbus, Ohio); and BAKELITE from Dow Chemical Company,Midland, Mich. Further details concerning suitable phenolic resins maybe found, for example, in U.S. Pat. No. 5,591,239 (Larson et al.) andU.S. Pat. No. 5,178,646 (Barber, Jr. et al.).

Exemplary epoxy resins include the diglycidyl ether of bisphenol A, aswell as materials that are commercially available under the tradedesignations EPON (e.g., EPON 828, EPON 1004, and EPON 1001F) fromMomentive, Houston, Tex.; and under the trade designations DER (e.g.,DER-331, DER-332, and DER-334) or DEN (e.g., DEN-431 and DEN-428) fromDow Chemical Company, Midland, Mich.

Exemplary urea-formaldehyde resins and melamine-formaldehyde resinsinclude those commercially available under the trade designationUFORMITE (e.g., from Reichhold Chemical, Durham, N.C.); DURITE (fromBorden Chemical Company, Columbus, Ohio); and RESIMENE (e.g., fromMonsanto, St. Louis, Mo.).

The nonwoven abrasive member may be manufactured through well-knownconventional processes that include steps such as, for example, applyinga curable binder precursor material (hereinafter referred to as “binderprecursor”) and abrasive particles to a lofty open nonwoven fiber webfollowed by curing the binder precursor. The abrasive particles may beapplied in combination with the binder precursor as a slurry, or moredesirably the abrasive particles may be applied (e.g., by dropping,blowing, or spraying) to the binder precursor after it is coated ontothe lofty open nonwoven fiber web. The binder precursor typicallycomprises a thermosetting resin and an effective amount of a curativefor the thermosetting resin. The binder precursor may also includevarious other additives such as, for example, fillers, plasticizers,surfactants, lubricants, colorants (e.g., pigments), bactericides,fungicides, grinding aids, and antistatic agents.

One exemplary method of making nonwoven abrasive members suitable foruse in practice of the present disclosure includes sequentially:applying a pre-bond coating to a nonwoven fiber web (e.g., byroll-coating or spray coating), curing the pre-bond coating,impregnating the pre-bonded nonwoven fiber web with a binder precursor(e.g., by roll-coating or spray coating), and curing the curablecomposition.

Typically, the binder precursor (including any solvent and abrasiveparticles that may be present) is coated onto the nonwoven fiber web inan amount of from 125 grams per square meter (gsm) to 2080 gsm, moretypically 500-2000 gsm, and even more typically 1250-1760 gsm, althoughvalues outside these ranges may also be used.

The binder precursor is typically applied to the fiber web in liquidform (e.g., by conventional methods), and subsequently hardened (e.g.,at least partially cured) to form a layer coated on at least a portionof the fiber web. Binder precursors utilized in practice according tothe present disclosure may typically be cured by exposure to, forexample, thermal energy (e.g., by direct heating, induction heating,and/or by exposure to microwave and/or infrared electromagneticradiation) and/or actinic radiation (e.g., ultraviolet light, visiblelight, particulate radiation). Exemplary sources of thermal energyinclude ovens, heated rolls, and/or infrared lamps.

In one exemplary method, a slurry coat precursor comprising abrasiveparticles and a binder precursor material is applied to the fiber weband then at least partially cured. Optionally, a second binder precursormaterial (i.e., a size coat precursor), which may be the same as ordifferent from the slurry coat precursor may be applied to the slurrycoat, typically after at least partially curing the slurry coatprecursor.

In another exemplary method, a make coat precursor comprising a firstbinder precursor is typically applied to the fiber web, abrasiveparticles are deposited on the make coat, and then the make coatprecursor is hardened (e.g., by evaporation, cooling, and/or at leastpartially curing). Subsequently, a second binder precursor (i.e., a sizecoat precursor), which may be the same as or different from the makecoat precursor, may typically applied over the make coat and abrasiveparticles, and then at least partially cured.

Typically, binder precursors employed in slurry coat precursors, or atleast one of make coat precursors and/or size coat precursors (e.g., asdescribed above), comprise a monomeric or polymeric material that may beat least partially cured (i.e., polymerized and/or crosslinked).Typically, upon at least partial curing, such binder precursors form anon-elastomeric binder (e.g., a hard brittle binder) that may have aKnoop hardness number (KHN, expressed in kilogram-force per squaremillimeter (kgf/mm²)) of, for example, at least about 20, at least about40, at least about 50, or even at least about 60, as measured inaccordance with ASTM Test Method D1474-98 (2002) “Standard Test Methodsfor Indentation Hardness of Organic Coatings”) that bonds abrasiveparticles to the fiber web.

Suitable methods for applying slurry coat precursors, make coatprecursors, size coat precursors, etc. are well known in the art ofnonwoven abrasive articles, and include coating methods such as curtaincoating, roll coating, spray coating, and the like. Typically, spraycoating is an effective and economical method for applying slurry coatand make coat precursors. The optional size coat may be elastomeric ornon-elastomeric and may contain various additives such as, for example,one or more of a lubricant and/or a grinding aid. The optional size coatmay comprise an elastomer (e.g., a polyurethane elastomer). Exemplaryuseful elastomers include those known for use as a size coat fornonwoven abrasive articles. For example, elastomers may be derived fromisocyanate-terminated urethane pre-polymers such as, for example, thosecommercially available under the trade designations VIBRATHANE orADIPRENE from Crompton & Knowles Corporation, Middlebury, Conn.; andMONDUR or DESMODUR from Bayer Corporation, Pittsburgh, Pa.

Optionally, the slurry coat, make coat, and/or size coat may furtherinclude one or more catalysts and/or curing agents to initiate and/oraccelerate the curing process (e.g., thermal catalyst, hardener,crosslinker, photocatalyst, thermal initiator, and/or photoinitiator) aswell as in addition, or alternatively, other known additives such as,for example, fillers, thickeners, tougheners, grinding aids, pigments,fibers, tackifiers, lubricants, wetting agents, surfactants, antifoamingagents, dyes, coupling agents, plasticizers, and/or suspending agents.Exemplary lubricants include metal stearate salts such as lithiumstearate and zinc stearate, or materials such as molybdenum disulfide,and mixtures thereof.

As used herein, the term “grinding aid” refers to a non-abrasive (e.g.,having a Mohs hardness of less than 7) particulate material that has asignificant effect on the chemical and physical processes of abrading.In general, the addition of a grinding aid increases the useful life ofa nonwoven abrasive. Exemplary grinding aids include inorganic andorganic materials, include waxes, organic halides (e.g., chlorinatedwaxes, polyvinyl chloride), halide salts (e.g., sodium chloride,potassium cryolite, cryolite, ammonium cryolite, potassiumtetrafluoroborate, sodium tetrafluoroborate, silicon fluorides,potassium chloride, magnesium chloride), metals (e.g., tin, lead,bismuth, cobalt, antimony, cadmium, iron, and titanium and theiralloys), sulfur, organic sulfur compounds, metallic sulfides, graphite,and mixtures thereof.

In one useful embodiment, exposure of the abrasive particles through aplasma etching process results in nonwoven abrasive articles whoseabrasive properties benefit by addition of an overlayer comprising afatty acid metal salt. FIG. 8 shows an example of a plasma-etchednonwoven abrasive article. It can be seen that the visible outer layerof abrasive particles bound along the fibers are not deeply embedded(e.g., they are highly exposed).

During plasma etching, the ionized plasma erodes or removes the binderfrom the outer surfaces of the nonwoven abrasive member, graduallyexposing more surface area of the underlying abrasive particles.

The conditions of the plasma treatment are adjusted for isotropicetching of the nonwoven abrasive member, uniformly eroding thecross-linked binder even though there are significant height andgeometry variations within the nonwoven abrasive member.

Plasma etching apparatus and conditions are well-known in the art.Briefly, during plasma treatment, plasma created in a vacuum chamberfrom gas within the chamber is generated and sustained by supplyingpower (for example, from an RF generator operating at a frequency in therange of 0.001 to 100 MHz) to at least one electrode. The electrodesystem may be symmetric or asymmetric. In some plasma apparatus,electrode surface area ratios between grounded and powered electrodesare from 2:1 to 4:1 or from 3:1 to 4:1. The powered electrode may becooled, e.g., with water. For discrete, relatively planar objects suchas abrasive articles, plasma deposition can be achieved, for example, byplacing the articles in direct contact with the smaller electrode of anasymmetric electrode configuration. This allows the article to act as anelectrode due to capacitive coupling between the powered electrode andthe article.

The RF power source provides power at a typical frequency in the rangeof 0.01 to 50 MHz, or 13.56 MHz or any whole number (e.g., 1, 2, or 3)multiple thereof. The RF power source can be an RF generator such as a13.56 MHz oscillator. To obtain efficient power coupling (i.e., whereinthe reflected power is a small fraction of the incident power), thepower source may be connected to the electrode via a network that actsto match the impedance of the power supply with that of the transmissionline (which is usually 50 ohms reactive) so as to effectively transmitRF power through a coaxial transmission line. One type of matchingnetwork, which includes two variable capacitors and an inductor, isavailable under the designation AMN 3000 from Plasmatherm of St.Petersburg, Fla. Traditional methods of power coupling involve the useof a blocking capacitor in the impedance matching network between thepowered electrode and the power supply. This blocking capacitor preventsthe DC bias voltage from being shunted out to the rest of the electricalcircuitry. Instead, the DC bias voltage is shunted out in a groundedelectrode. While the acceptable frequency range from the RF power sourcemay be high enough to form a large negative DC self bias on the smallerelectrode, it should not be so high that it creates standing waves inthe resulting plasma, which is inefficient for plasma treatment.

In addition to batch treatment of the abrasive articles, rolls orcontinuous webs of nonwoven abrasive material can be treated using acontinuous plasma reactor using techniques as described in U.S. Pat. No.5,888,594 (David et al.); U.S. Pat. No. 5,948,166 (David et al.); U.S.Pat. No. 7,195,360 (Bacon et al.); and in U.S. Patent Appin. Publ. No.2003/0134515 A1 (David et al.). A continuous plasma treatment apparatustypically includes a rotating drum electrode which may be powered by aradio frequency (RF) power source, a grounded chamber which acts as agrounded electrode, a feed reel which continuously suppliesto-be-treated articles in the form of a continuous moving web, and atake-up reel which collects the treated article. The feed and take upreels are optionally enclosed within the chamber, or can be operatedoutside of the chamber as long as a low-pressure plasma can bemaintained within the chamber. If desired, a concentric groundedelectrode can be added near the powered drum electrode for additionalspacing control. An inlet supplies suitable treatment gases in vapor orliquid form to the chamber.

The nonwoven abrasive material is preferably uniformly plasma treated byusing alone or in combination, higher gas pressures, longer treatmenttimes, higher power settings, or fluorocarbon (e.g., perfluoropropane(i.e., C₃F₈)) gases in combination with oxygen (i.e., O₂) to provideisotropic plasma etching conditions. The isotropic plasma etchingconditions can use either pure oxygen gas at higher pressures or acombination of O₂ and C₃F₈ gases at lower pressures. Treatment gaspressures are generally from 50 to 10,000 milliTorr (7 to 1300 Pa), orfrom 60 to 1,000 milliTorr (8 to 170 Pa), or from 250 to 550 milliTorr(33 to 73 Pa). Treatment times are generally from 2 minutes to 15minutes, or from 4 minutes to 12 minutes, or from 5 minutes to 10minutes, although this is not a requirement. Treatment gases include,for example, either pure oxygen or a mixture of oxygen and C₃F₈ gases. Aratio for the flow rate of the C₃F₈ gas divided by a total combined flowrate of the C₃F₈ gas and the O₂ gas is generally from 0.10 to 0.30 orfrom 0.15 to 0.25, and the total combined gas flow rates are typically0.1 to 10 liters/minute. Treatment power for the plasma etching processis generally set at from 0.1 to 1.0 watts/cm² of the electrode area.

The nonwoven abrasive member may be in any suitable form. Examplesinclude webs, discs, pads, belts, and/or sheets.

The overlayer composition includes at least one fatty acid metal salt(i.e., a salt of a metal and at least one fatty acid). Useful fatty acidmetal salts include, for example, metal salts of carboxylic acidsrepresented by the formula R—CO₂H wherein R represents an aliphaticgroup having at least 7 carbon atoms, preferably at least 11 carbonatoms, and more preferably at least 18 carbon atoms. In someembodiments, R is represented by the formula CH₃(CH₂)_(n)CO₂H wherein nis an integer and is at least 7, preferably at least 9, at least 11, atleast 13, at least 15, or even at least 17. Although there is nospecific limitation on the types of fatty acids, metal salts of fattyacids staying solid in room temperature are typically preferred.Examples of saturated fatty acids that may be used include caprylicacid, capric acid, lauric acid, myristic acid, palmitic acid, stearicacid, arachidic acid, behenic acid, lignoceric acid, and montanic acid.Examples of unsaturated fatty acids include undecylenic acid, decenoicacid, sapienic acid, vaccenic acid, oleic acid, erucic acid, linoleicacid, α-linolenic acid, and arachidonic acid. Among them, preferredfatty acids are capric acid, lauric acid, myristic acid, palmitic acid,stearic acid, behenic acid, montanic acid, and undecylenic acid, andmore preferably stearic acid, palmitic acid, myristic acid, lauric acid,behenic acid, and montanic acid.

Exemplary of metals included in the metal salt of the fatty acid includecalcium, zinc, magnesium, aluminum, barium, lithium, sodium, potassium,calcium and silver. Preferred metals include calcium, zinc, lithium, andbarium. Combinations of two or more metal salts of fatty acids may alsobe used. A plurality of different metal salts of fatty acids may enablewetting tension of the overlayer composition to be controlled.

A binder may be included in the overlayer composition. Suitable bindersinclude, for example, alkyl cellulose resins (e.g., methyl cellulose andethyl cellulose), acrylic resins, alkylamide resins, vinyl acetateresins, styrene-acrylonitrile resins, styrene-butadiene rubbers,butadiene rubbers, natural rubber, chloroprene rubbers andmethylbutadiene rubbers. Two or more binding resins may be used incombination.

The overlayer composition may optionally further comprise additives suchas, for example, surface-active agents, plasticizers, antistatic agents,humidifying agents, antifoaming agents, coloring materials, pigments,filler, and combinations thereof.

The overlayer composition may be prepared by mixing a fatty acid metalsalt and a binder, optionally in the presence of a liquid medium (e.g.,water and/or a suitable organic solvent), if desired.

The content of the metal salt of the fatty acid in the overlayercomposition for coating may be in a range of from 10 to 100 weightpercent on a dry weight basis, more typically from 60 to 100 percent,although other amounts may be used.

The abrasive particles are distributed within the nonwoven abrasivemember, but have a visible outer layer adjacent to at least one majorsurface of the lofty open fiber web. The overlayer composition isdisposed on at least a portion of the visible outer layer of abrasiveparticles. While the overlayer composition may cover more abrasiveparticles, in general it is only the outer abrasive particles thatcontact a surface of a workpiece to be abraded, and hence the greatestbenefit is seen when they are contacted by the overlayer composition.

The overlayer composition may be applied to only a portion of the majorsurface of the nonwoven abrasive member; for example, so as not to coversome of the abrasive particles adjacent to major surfaces of the loftyopen fiber web, or it may be applied to the major surface. The overlayermay be applied before or after the abrasive member coatings are finallycured.

There is no specific limitation on how to apply the overlayercomposition to the major surface(s) nonwoven abrasive member. Forexample, it may be applied by means of brush coating, roll coating, flowcoating, die coating, spray coating and the like onto the abrasivesurface (i.e., a surface which exerts abrasive action by contacting aworkpiece). The quantity of overlayer composition to be applied onto theabrasive surface can vary in an appropriate manner with the size andquantity of abrasive particles to be used and the intended applicationof the abrasive article. Generally, it is approximately 1 to 200 gsm asdried coating weight, and preferably approximately 9 to 40 gsm, althoughother dried coating weights may also be used.

After the overlayer composition is applied onto the abrasive surface, itmay be heated and dried under proper conditions of temperature and timeuntil the binding resin is formed into a film. The heating conditionsmay be determined in an appropriate manner.

Nonwoven abrasive articles according to the present disclosure areuseful for abrading a workpiece. One such method includes frictionallycontacting a nonwoven abrasive article with a surface of the workpiece,and moving at least one of the nonwoven abrasive article or theworkpiece relative to the other to abrade at least a portion of thesurface. Examples of workpiece materials include metal, metal alloys,exotic metal alloys, ceramics, glass, wood, wood-like materials,composites, painted surfaces, plastics, reinforced plastics, stone,and/or combinations thereof. The workpiece may be flat or have a shapeor contour associated with it. Exemplary workpieces include metalcomponents, plastic components, particleboard, camshafts, crankshafts,furniture, and turbine blades.

Nonwoven abrasive articles according to the present disclosure may beused by hand and/or used in combination with a machine. Abrading may beconducted under wet or dry conditions. Exemplary liquids for wetabrading include water, water containing conventional rust inhibitingcompounds, lubricant, oil, soap, and cutting fluid. The liquid may alsocontain, for example, defoamers, and/or degreasers.

Further details concerning nonwoven abrasive articles, abrasive wheelsand methods for their manufacture may be found, for example, in U.S.Pat. No. 2,958,593 (Hoover et al.); U.S. Pat. No. 5,591,239 (Larson etal.); U.S. Pat. No. 6,017,831 (Beardsley et al.); and U.S. Patent Appin.Publ. No. 2006/0041065 A1 (Barber).

SELECT EMBODIMENTS OF THE PRESENT DISCLOSURE

In a first embodiment, the present disclosure provides a nonwovenabrasive article comprising:

a) a nonwoven abrasive member having a working surface, wherein thenonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;    -   abrasive particles adhered to at least a portion of the fibers        by a binder material, wherein at least a portion of the abrasive        particles form a visible outer layer of the abrasive particles        along the fibers adjacent to the working surface of the nonwoven        abrasive member, wherein the abrasive particles in the visible        outer layer are closely packed, and wherein on a numerical basis        at least 80 percent of the abrasive particles in the visible        outer layer have recognizable outlines; and

b) an overlayer composition disposed on at least a portion of thevisible outer layer of the abrasive particles thereby forming thenonwoven abrasive article, wherein the overlayer composition comprises afatty acid metal salt.

In a second embodiment, the present disclosure provides a nonwovenabrasive article according to the first embodiment, wherein the visibleouter layer of the abrasive particles comprises crevices disposedbetween adjacent ones of the abrasive particles.

In a third embodiment, the present disclosure provides a nonwovenabrasive article according to the first or second embodiment, wherein atleast a portion of the abrasive particles in the visible outer layer ofthe abrasive particles overlap one another.

In a fourth embodiment, the present disclosure provides a nonwovenabrasive article according to any one of the first to third embodiments,wherein the overlayer composition has a basis weight of at least 2.5grams per square meter.

In a fifth embodiment, the present disclosure provides a nonwovenabrasive article according to any one of the first to fourthembodiments, wherein the overlayer composition further comprises apolymeric resin.

In a sixth embodiment, the present disclosure provides a nonwovenabrasive article according to any one of the first to fifth embodiments,wherein the abrasive particles have an average particle size of at least5 microns.

In a seventh embodiment, the present disclosure provides a nonwovenabrasive article according to any one of the first to sixth embodiments,wherein the abrasive particles conform to an abrasives industryspecified nominal grade.

In an eighth embodiment, the present disclosure provides a method ofmaking an abrasive article, the method comprising:

a) providing a nonwoven abrasive member having a working surface,wherein the nonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;    -   abrasive particles adhered to at least a portion of the fibers        by a binder material, wherein    -   at least a portion of the abrasive particles form a visible        outer layer of the abrasive particles along the fibers adjacent        to the working surface of the nonwoven abrasive member, wherein        the abrasive particles in the visible outer layer are closely        packed, and wherein on a numerical basis at least 80 percent of        the abrasive particles in the visible outer layer have        recognizable outlines; and

b) disposing an overlayer composition on at least a portion of thevisible outer layer of the abrasive particles thereby forming thenonwoven abrasive article, wherein the overlayer composition comprises afatty acid metal salt.

In a ninth embodiment, the present disclosure provides a nonwovenabrasive article according to the eighth embodiment, wherein the visibleouter layer of the abrasive particles comprises crevices disposedbetween adjacent ones of the abrasive particles.

In a tenth embodiment, the present disclosure provides a nonwovenabrasive article according to the seventh or eighth embodiment, whereinat least a portion of the abrasive particles in the visible outer layerof the abrasive particles overlap one another.

In an eleventh embodiment, the present disclosure provides a methodaccording to any one of the eighth to tenth embodiments, wherein theoverlayer composition has a basis weight of at least 2.5 grams persquare meter.

In a twelfth embodiment, the present disclosure provides a nonwovenabrasive article having a working surface, wherein the nonwoven abrasivemember comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;        and    -   abrasive particles adhered to the fibers by a binder material,        wherein the working surface of the nonwoven abrasive member has        a kinetic coefficient of friction of at least 0.54 according to        the FRICTION TEST described herein; and

an overlayer composition disposed on at least a portion of the bindermaterial and abrasive particles adjacent to the working surface therebyforming the nonwoven abrasive article, wherein the overlayer compositioncomprises a fatty acid metal salt.

In a thirteenth embodiment, the present disclosure provides a nonwovenabrasive article according to the twelfth embodiment, wherein theoverlayer composition has a basis weight of at least 2.5 grams persquare meter.

In a fourteenth embodiment, the present disclosure provides a nonwovenabrasive article according to the twelfth or thirteenth embodiment,wherein the overlayer composition further comprises a polymeric resin.

In a fifteenth embodiment, the present disclosure provides a nonwovenabrasive article according to any one of the twelfth to fourteenthembodiments, wherein the abrasive particles have an average particlesize of at least 5 microns.

In a sixteenth embodiment, the present disclosure provides a nonwovenabrasive article according to any one of the twelfth to fifteenthembodiments, wherein the abrasive particles have an average particlesize of less than or equal to 125 microns.

In a seventeenth embodiment, the present disclosure provides a nonwovenabrasive article according to any one of the twelfth to sixteenthembodiments, wherein the abrasive particles conform to an abrasivesindustry specified nominal grade.

In an eighteenth embodiment, the present disclosure provides a method ofmaking an abrasive article, the method comprising:

providing a nonwoven abrasive member having a working surface, whereinthe nonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;    -   abrasive particles adhered to the fibers by a binder material,        wherein the working surface of the nonwoven abrasive member has        a kinetic coefficient of friction of at least 0.54 according to        the FRICTION TEST described herein; and

disposing an overlayer composition on at least a portion of the bindermaterial and the abrasive particles adjacent to the working surfacethereby forming the nonwoven abrasive article, wherein the overlayercomposition comprises a fatty acid metal salt.

In a nineteenth embodiment, the present disclosure provides a methodaccording to the eighteenth embodiment, wherein the overlayercomposition has a basis weight of at least 2.5 grams per square meter.

In a twentieth embodiment, the present disclosure provides a method ofmaking an abrasive article, the method comprising:

a) providing a nonwoven abrasive member having a working surface,wherein the nonwoven abrasive member comprises:

-   -   a lofty open fiber web comprising fibers bonded to one another;        and    -   abrasive particles adhered to at least a portion of the fibers        by a binder material, wherein at least a portion of the abrasive        particles are at least partially embedded in the binder        material; and

b) plasma-etching a portion of the binder material adjacent to theworking surface to expose portions of the abrasive particles previouslyembedded in the binder material to provide a plasma-etched nonwovenabrasive member; and

c) disposing an overlayer composition on at least a portion of theworking surface of the plasma-etched nonwoven abrasive member, whereinthe overlayer composition comprises a fatty acid metal salt.

In a twenty-first embodiment, the present disclosure provides a methodaccording to the twentieth embodiment, wherein the abrasive particleshave an average particle size of less than or equal to 125 microns.

In a twenty-second embodiment, the present disclosure provides a methodaccording to the twentieth or twenty-first embodiment, wherein theoverlayer composition has a basis weight of at least 2.5 grams persquare meter.

Objects and advantages of this disclosure are further illustrated by thefollowing non-limiting examples, but the particular materials andamounts thereof recited in these examples, as well as other conditionsand details, should not be construed to unduly limit this disclosure.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in theExamples and the rest of the specification are by weight.

Abbreviations for materials used in the Examples are reported in Table1, below.

TABLE 1 ABBREVIATION DESCRIPTION Fiber 15 denier (17 dTex) × 1.5 inches(3.8 cm) staple length High Tenacity Nylon 66 fiber produced by EMSCHEMIE, Austria water tap water PMA propylene glycol monomethyl etheracetate, obtained from Ashland Chemical Co., Columbus, Ohio K450 LAPOXK-450 aromatic amine hardener diluted to 42.3 weight percent in PMA,from Royce International, East Rutherford, New Jersey. BL16 polyurethaneprepolymer, obtained as ADIPRENE BL-16 from Chemtura Corporation,Middlebury, Connecticut GEO anti-foam agent, obtained as GEO FM LTX fromGEO Specialty Chemicals, Ambler, Pennsylvania P1 red pigment, aqueousdispersion, obtained as RPD-0210 from Sun Chemical Corporation,Cincinnati, Ohio PME propylene glycol monomethyl ether, obtained fromDow Chemical Corporation, Midland, Michigan SR 75% hydroxyethyl ethyleneurea in Water, obtained as SR511A from Sartomer Inc., Exton,Pennsylvania S1 ethoxylated nonionic surfactant, obtained as DYNOL 604from Air Products and Chemicals Inc., Allentown, Pennsylvania S2secondary alcohol ethoxylate, nonionic surfactant, obtained as TERGITOL15-S-5 from Dow Chemical Company Resin phenolic resin obtained asPREFERE 80 5077A from Arclin, Mississauga, Ontario, Canada AP280 DURALUMG52 brown aluminum oxide abrasive particles, grade 280/600, fromWashington Mills Electro Minerals Corp., Niagara Falls, New York P2carbon black pigment, obtained as C-SERIES BLACK 7 LCD4115 from SunChemical Corporation, Cincinnati, Ohio AP1500 silicon carbide, black,grade P1500, obtained from GNP Ceramics LLC, Clarence Center, New YorkL1 a 1.52 wt. % dispersion of LAPONITE synthetic clay (Southern ClayProducts, Inc. Gonzales, Texas) in a mixture of 84.4 wt. % of water,14.07 wt. % PME and 0.01 wt. % GEO CaSt calcium stearate solution,consisting of 67-68 wt. % of water, 28.8 wt. % of C14-18 calciumstearate, 3.2 wt. % of polyacrylate emulsion and 0.5-1.0 wt. % ammoniumsalt of modified polymer. LiSt lithium stearate solution consisting of79.5 wt. % water, 18 wt. % C14-18 lithium stearate, 2 wt. %polystyrene-acrylate emulsion (obtained as JONCRYL 89 from BASF, FlorhamPark, New Jersey), and 0.5 wt. % sodium lauryl sulfate NaSt Sodiumstearate solution consisting of 80.05 wt. % water, 18 wt. % C14-18sodium stearate, 1.45 wt. % polystyrene-acrylate emulsion (obtained asJONCRYL 89 from BASF), 0.25 wt. % sodium lauryl sulfate and 0.25% ofMETHOCEL (from Dow Chemical. NaSt1 Sodium stearate solution consistingof 84.5 wt. % water, 15 wt. % C14-18 sodium stearate, 0.25 wt. % sodiumlauryl sulfate and 0.25% METHOCEL from Dow Chemical. CaSt1 Calciumstearate solution consisting of 84.5 wt. % water, 15 wt. % C14-18calcium stearate, 0.25 wt. % sodium lauryl sulfate and 0.25 wt. %METHOCEL cellulose ether from Dow Chemical. BaSt Barium stearatesolution (30 wt. % in water) obtained as EC1686 from eChem Ltd, Leeds,UK. P3 Black dye solution containing 45 wt. % of PME, 45 wt. % of waterand 10 wt. % of ELCACID NIGROSINE WSJ black dye obtained from GreenvilleColorants, LLC, East Jersey City, New Jersey P4 Red dye solutionconsisting of 89.2 wt. % of PME, 4.1 wt. % of P3, and 6.7 wt. % ofDISPERSE RED 17 obtained from American Dyestuff Corp., Clifton, NewJersey.

Test Procedures Schiefer Test

Two nonwoven abrasive article test specimens were prepared as 10.2-cmdiameter discs that are stacked and then secured to a foam back-up padby means of a hook-and-loop fastener. The back-up pad/fastener assemblyhad a Shore Durometer OO hardness of 85. The abrasive disc and back-uppad assembly was installed on a Schiefer Uniform Abrasion Tester(available from Frazier Precision Instrument Company, Inc. Hagerstown,Md.), and the abrasive disc was used to abrade an annular ring (10.2 cmoutside diameter (OD)×5.1 cm inside diameter (ID)) of cellulose acetatebutyrate polymer from Seelye-Eiler Plastics Inc., Bloomington, Minn. Theload was 5 lb (2.27 kg). The test duration was 8 periods of 500revolutions or cycles of the abrasive disc (4000 cycles total). Theamount of cellulose acetate butyrate polymer removed was measured at theend of each 500-cycle test period.

KCF Test

This procedure follows that of the FRICTION TEST with the followingadditional details. The friction testing machine was a Thwing-AlbertFriction/Peel Tester Model 225-100, obtained from Thwing-AlbertInstrument Company, West Berlin, N.J.

The friction testing machine was set for a 500-gram load, a 5-secondtest time, and a speed of 31 cm/min (speed setting “D”). The weightedtest specimen was placed on the test surface and attached to the testingmachine by a metal hook. The test machine was zeroed and the testinitiated. Three specimens were tested for each example.

Example 1

Nonwoven abrasive test specimens were prepared and tested both with andwithout an overlayer coating of CaSt.

A lightweight, open, low-density air-laid nonwoven web was prepared fromFiber using a RANDO-WEBBER machine, commercially available from theRando Machine Corporation of Macedon, N.Y. The resulting lofty openfiber web had a nominal basis weight of 37 grains per 24 square inches(155 gsm), and the thickness was 0.35 inches (9 mm) The web was conveyedto a horizontal two-roll coater, where a pre-bond resin consisting of74.89 wt. % of PMA, 5.53 wt. % of K450, 15.07 wt. % of BL16, 0.01 wt. %of GEO, and 4.5 wt. % of P4 was applied to the fiber web at a wet add-onweight of 7 grains/24 square inches (29.3 gsm).

The coated web was conveyed through an oven maintained at 163-177° C.with a residence time of 3 minutes. The resulting pre-bonded fiber webwas conveyed to a spray booth where a resin/abrasive slurry consistingof 19.11 wt. % of L1, 0.40 wt. % of P1, 1.60 wt. % of SR, 0.10 wt. % of51, 13.58 wt. % of Resin, 1.00 wt. % of S2, and 64.22 wt. % of AP280 wassprayed on the top surface of the web. Within the booth, spray nozzles(which are mounted to reciprocate perpendicularly to the direction ofweb movement) apply the slurry at a wet weight of about 67 grains/24square inch (280 gsm).

The slurry-coated web was then heated in an oven maintained at 177° C.for 3 minutes. The web was then inverted and the slurry spray coatingwas applied to the opposite side of the web. The coated web was finallyheated in an oven maintained at 177° C. for 3 minutes, to yield anonwoven abrasive member (shown in FIG. 2) which was tested according tothe Schiefer Test and the KCF Test. Test results are reported in Table2.

The nonwoven abrasive member was then brushed with a uniform coating ofa 16 wt. % solids CaSt solution and heated in a forced convection ovenmaintained at 95° C. for 20 minutes to achieve a dry add-on of 18grains/24 square inches (75 gsm). The resulting article was testedaccording to the Schiefer Test and the results reported in Table 2. Thedifference in the Schiefer Test results for the uncoated nonwovenabrasive article and the CaSt-coated nonwoven abrasive article are alsoreported in Table 2.

Examples 2-4 and Comparative Examples A-B

Example 2 and Comparative Examples A and B were further embodiments withalumina abrasive particles, and were made identically to Example 1,except that, in the case of Comparative Example A only, the prebondcomposition consisted of 53.21 wt. % of PMA, 17.94 wt. % of ten degreexylene, 7.74 wt. % K450, 21.1 wt. % BL16, and 0.01 wt. % GEO, and theslurry spray compositions were as reported in Table 3. The resultingnonwoven abrasive members were tested according to the Schiefer Test andthe KCF Test. The CaSt solution was then applied as recited in Example 1and the resulting nonwoven abrasive members (shown in respective FIGS.3-5) were tested according to the Schiefer Test. Results are reported inTable 2.

Example 3 (shown in FIG. 6) was a MIRKA MIRLON 18-111-447 SCUFF PADnonwoven abrasive handpad, obtained from Mirka Abrasives, Inc.,Twinsburg, Ohio.

Example 4 (shown in FIG. 7) was a NORTON BEAR-TEX 74700 nonwovenabrasive hand pad, obtained from Saint-Gobain Abrasives Inc., Worcester,Mass.

Example 5

Example 5 was prepared to demonstrate the effect of particle exposure onthe efficacy of the CaSt coating. Example 5 was made by exposing thenonwoven abrasive member of Comparative Example B to a plasma treatmentprocess as described in Example 1 of U.S. Patent Appin. Publ. No.2010/0255254 A1 (Culler et al.), with the exception that the treatmenttime was 20 minutes instead of 10 minutes. The kinetic coefficient offriction and the cut of Example 5 were then measured both with andwithout the CaSt coating, as in the previous Examples. The resultingnonwoven abrasive member is shown in FIG. 8, and the test results arereported in Table 2.

Examples 6-12 and Comparative Example C

Examples 6-8 and Comparative Example C were made identically to Example1, except that the pre-bond composition was 78.98% PMA, 5.6% K450,15.26% BL16, 0.01% GEO, and 0.151.16% P2; and the slurry spraycompositions was that shown in Table 3. The resulting nonwoven abrasivemembers (shown in respective FIGS. 9-12) were tested according to theSchiefer Test and the KCF Test.

The CaSt solution was then applied as recited in Example 1, and theresulting nonwoven abrasive articles were tested according to theSchiefer Test. Results are reported in Table 2.

Example 9 (shown in FIG. 13) was MIRKA MIRLON 18-111-448 SCUFF PADnonwoven abrasive handpad, obtained from Mirka Abrasives, Inc.

Example 10 (shown in FIG. 14) was a NORTON BEAR-TEX 74800 nonwovenabrasive hand pad, obtained from Saint-Gobain Abrasives Inc.

Example 11 (shown in FIG. 15) was a SCOTCH-BRITE DURABLE FLEX S ULFnonwoven abrasive hand pad from 3M Company, Saint Paul, Minn.

Example 12 (shown in FIG. 16) was a SCOTCH-BRITE 7448B nonwoven abrasivehand pad from 3M Company.

Examples 13-19

Examples 13-19 were prepared to show the effects of type of stearate atvarious add-ons, and were prepared identically to Example 7, with theexception that either CaSt or LiSt was applied topically according tothe compositions reported in Table 4. Schiefer Test results for uncoatedand variously coated examples are reported in Table 4. FIGS. 17-23 showthe nonwoven abrasive members used in Examples 13-19, respectively.

Examples 20 and 21

Examples 17 and 18 were a repeat of Example 7, with the exception that aconstant amount of two different metal salts was applied as reported inTable 4.

Examples 22-25

Examples 22-25 were prepared to show the effects of various metalstearate salts with the same add-on weight (18 gsm), and were preparedidentically to Example 7, with the exception that either CaSt1, NaSt,NaSt1, or BaSt was applied topically according to the compositionsreported in Table 5, and Examples 22 and 23 were prepared without abinder in the overlayer composition. Schiefer Test results for uncoatedand variously coated examples are reported in Table 5.

TABLE 2 KCF TEST SCHIEFER TEST CUT Kinetic No CaSt With CaSt CoefficientStandard Overlayer, Overlayer, % EXAMPLE of Friction Deviation gramsgrams Change Comparative 0.45 0.01 0.251 0.154 −39 Example A Comparative0.51 0.03 0.315 0.238 −25 Example B 1 0.59 0.03 0.677 1.344 +98.5 2 0.670.01 0.643 1.850 +188 3 0.64 0.03 0.570 0.760 +14 4 0.71 0.01 0.6000.980 +63 5 0.59 0.04 0.339 0.415 +23 6 0.67 0.02 0.195 0.403 +106 70.57 0.02 0.303 0.517 +70 8 0.63 0.02 0.200 0.340 +71 Comparative 0.500.05 0.108 0.086 −20 Example C 9 0.57 0.03 0.219 0.339 +55 10 0.56 0.030.166 0.288 +73 11 0.65 0.03 0.180 0.350 +94 12 0.55 0.02 0.240 0.590+146

TABLE 3 PARTS BY WEIGHT AP AP AP AP EXAMPLE L1 P1 SR S1 Resin S2 280 600400 1500 water PME P2 Comparative 12.98 0.91 3.66 0.23 31.02 2.28 48.910 0 0 0 0 0 Example A Comparative 14.49 0.79 3.15 0.20 26.73 1.97 52.680 0 0 0 0 0 Example B 1 19.11 0.40 1.60 0.10 13.58 1.00 64.22 0 0 0 0 00 2 20.16 0.31 1.25 0.08 10.60 0.78 66.83 0 0 0 0 0 0 5 19.11 0.4 1.60.1 13.58 1 64.21 0 0 0 0 0 0 6 12.49 0 1.41 0.07 13.88 0.35 0 0 0 59.2510.71 1.78 0.05 7 12.15 0 1.62 0.08 15.92 0.40 0 0 0 57.61 10.42 1.740.06 8 10.88 0 2.41 0.12 23.64 0.60 0 0 0 51.39 9.32 1.55 0.09Comparative 10.01 0 2.95 0.15 28.91 0.73 0 0 0 47.14 8.58 1.43 0.11Example C

TABLE 4 SCHIEFER TEST 500 CYCLES CUT 4000 CYCLES CUT CaSt add-on, LiStadd-on, No With No With grains/24 in² grains/24 in² Stearate, Stearate,Stearate, Stearate, EXAMPLE (gsm) (gsm) grams grams grams grams % Change13 0.5 (1.86)  0 0.068 0.085 0.303 0.405 34 14 1.5 (5.58)  0 0.068 0.0820.303 0.392 29 15 3 (11.16) 0 0.068 0.101 0.303 0.54 78 16 9 (33.49) 00.068 0.101 0.303 0.604 99 17 30 (111.65) 0 0.068 0.134 0.303 0.625 10618 69 (256.79) 0 0.068 0.106 0.303 0.606 100 19 90 (334.95) 0 0.0680.088 0.303 0.529 75 20 0 18 (66.99) 0.068 0.145 0.303 0.534 76 21 18(66.99)  0 0.068 0.133 0.303 0.544 79

TABLE 5 SCHIEFER TEST 500 CYCLES CUT 4000 CYCLES CUT METAL No StearateWith Stearate No Stearate With Stearate STEARATE Overlayer, Overlayer,Overlayer, Overlayer, EXAMPLE COMPOSITION grams grams grams grams %Change 22 CaSt1 0.068. 0.138 0.303 0.532 +76 23 NaSt1 0.068 0.136 0.3030.515 +70 24 NaSt 0.068 0.112 0.303 0.507 +67 25 BaSt 0.068 0.125 0.3030.636 +109

All cited references, patents, or patent applications in the aboveapplication for letters patent are herein incorporated by reference intheir entirety in a consistent manner. In the event of inconsistenciesor contradictions between portions of the incorporated references andthis application, the information in the preceding description shallcontrol. The preceding description, given in order to enable one ofordinary skill in the art to practice the claimed disclosure, is not tobe construed as limiting the scope of the disclosure, which is definedby the claims and all equivalents thereto.

1-22. (canceled)
 23. A nonwoven abrasive article comprising: a) anonwoven abrasive member having a working surface, wherein the nonwovenabrasive member comprises: a lofty open fiber web comprising fibersbonded to one another; abrasive particles adhered to at least a portionof the fibers by a binder material, wherein at least a portion of theabrasive particles form a visible outer layer of the abrasive particlesalong the fibers adjacent to the working surface of the nonwovenabrasive member, wherein the abrasive particles in the visible outerlayer are closely packed, and wherein on a numerical basis at least 80percent of the abrasive particles in the visible outer layer haverecognizable outlines; and b) an overlayer composition disposed on atleast a portion of the visible outer layer of the abrasive particlesthereby forming the nonwoven abrasive article, wherein the overlayercomposition comprises a fatty acid metal salt.
 24. The nonwoven abrasivearticle of claim 23, wherein the visible outer layer of the abrasiveparticles comprises crevices disposed between adjacent ones of theabrasive particles.
 25. The nonwoven abrasive article of claim 23,wherein at least a portion of the abrasive particles in the visibleouter layer of the abrasive particles overlap one another.
 26. Thenonwoven abrasive article of claim 23, wherein the overlayer compositionhas a basis weight of at least 2.5 grams per square meter.
 27. Thenonwoven abrasive article of claim 23, wherein the overlayer compositionfurther comprises a polymeric resin.
 28. The nonwoven abrasive articleof claim 23, wherein the abrasive particles have an average particlesize of at least 5 microns.
 29. The nonwoven abrasive article of claim23, wherein the abrasive particles conform to an abrasives industryspecified nominal grade.
 30. A method of making an abrasive article, themethod comprising sequentially: a) providing a nonwoven abrasive memberhaving a working surface, wherein the nonwoven abrasive membercomprises: a lofty open fiber web comprising fibers bonded to oneanother; abrasive particles adhered to at least a portion of the fibersby a binder material, wherein at least a portion of the abrasiveparticles form a visible outer layer of the abrasive particles along thefibers adjacent to the working surface of the nonwoven abrasive member,wherein the abrasive particles in the visible outer layer are closelypacked, and wherein on a numerical basis at least 80 percent of theabrasive particles in the visible outer layer have recognizableoutlines; and b) disposing an overlayer composition on at least aportion of the visible outer layer of the abrasive particles therebyforming the nonwoven abrasive article, wherein the overlayer compositioncomprises a fatty acid metal salt.
 31. The method of claim 30, whereinthe visible outer layer of the abrasive particles comprises crevicesdisposed between adjacent ones of the abrasive particles.
 32. The methodof claim 30, wherein at least a portion of the abrasive particles in thevisible outer layer of the abrasive particles overlap one another. 33.The method of claim 30, wherein the overlayer composition has a basisweight of at least 2.5 grams per square meter.
 34. A nonwoven abrasivearticle comprising: a nonwoven abrasive member having a working surface,wherein the nonwoven abrasive member comprises: a lofty open fiber webcomprising fibers bonded to one another; and abrasive particles adheredto the fibers by a binder material, wherein the working surface of thenonwoven abrasive member has a kinetic coefficient of friction of atleast 0.54 according to the FRICTION TEST described herein; and anoverlayer composition disposed on at least a portion of the bindermaterial and abrasive particles adjacent to the working surface therebyforming the nonwoven abrasive article, wherein the overlayer compositioncomprises a fatty acid metal salt.
 35. The nonwoven abrasive article ofclaim 34, wherein the overlayer composition has a basis weight of atleast 2.5 grams per square meter.
 36. The nonwoven abrasive article ofclaim 34, wherein the overlayer composition further comprises apolymeric resin.
 37. The nonwoven abrasive article of claim 34, whereinthe abrasive particles have an average particle size of at least 5microns.
 38. The nonwoven abrasive article of claim 34, wherein theabrasive particles have an average particle size of less than or equalto 125 microns.
 39. The nonwoven abrasive article of claim 34, whereinthe abrasive particles conform to an abrasives industry specifiednominal grade.
 40. A method of making an abrasive article, the methodcomprising sequentially: providing a nonwoven abrasive member having aworking surface, wherein the nonwoven abrasive member comprises: a loftyopen fiber web comprising fibers bonded to one another; abrasiveparticles adhered to the fibers by a binder material, wherein theworking surface of the nonwoven abrasive member has a kineticcoefficient of friction of at least 0.54 according to the FRICTION TESTdescribed herein; and disposing an overlayer composition on at least aportion of the binder material and the abrasive particles adjacent tothe working surface thereby forming the nonwoven abrasive article,wherein the overlayer composition comprises a fatty acid metal salt. 41.The method of claim 40, wherein the overlayer composition has a basisweight of at least 2.5 grams per square meter.
 42. A method of making anabrasive article, the method comprising: a) providing a nonwovenabrasive member having a working surface, wherein the nonwoven abrasivemember comprises: a lofty open fiber web comprising fibers bonded to oneanother; and abrasive particles adhered to at least a portion of thefibers by a binder material, wherein at least a portion of the abrasiveparticles are at least partially embedded in the binder material; and b)plasma-etching a portion of the binder material adjacent to the workingsurface to expose portions of the abrasive particles previously embeddedin the binder material to provide a plasma-etched nonwoven abrasivemember; and c) disposing an overlayer composition on at least a portionof the working surface of the plasma-etched nonwoven abrasive member,wherein the overlayer composition comprises a fatty acid metal salt. 43.The method of claim 42, wherein the abrasive particles have an averageparticle size of less than or equal to 125 microns.
 44. The method ofclaim 42, wherein the overlayer composition has a basis weight of atleast 2.5 grams per square meter.